Rust preventative compositions



Edgar A. Dieman,

UnitedStates Patent I O 2,875,072 Rnsr PREVENTATIYE COMPOSITIONS CrownPoint, and James W. Gaynor, Valparaiso, Ind., assignors to Standard OilCompany, Chicago, 111., a corporation of Indiana No Drawing. ApplicationJune 29, 1955 Serial No. 518,978

4 Claims. (Cl. 106-14) Our invention relates .to rust preventativecompositions, of the slashing oil type, which have particular value forprotecting metal surfaces in acid atmospheres.

Various organic acids have been proposed for use in oil compositions forpreventing rusting of metal surfaces in acid atmospheres. Althougharomatic acids have considerable effectiveness, their practicaleffectiveness is substantially reduced by their relative insolubility inhydrocarbon oils. Efforts have been made to solubilize such materials toan extent permitting practical utilization wit out interfering with orreducing their rust inhibiting capacities. This, however, has proveddifiicult to accomplish and, accordingly, it is an object of ourinvention to provide a rust preventative composition of improvedproperties for use in acid atmospheres.

We have found that the combination of a higher aliphatic primary aminewith an aromatic acid, e. g., benzoic acid, when used in conjunctionwith Zinc naph thenate in mineral oil provides an unusually eifectivecorrosion and rust inhibiting composition. The ingredients havesufficient solubility in light hydrocarbon oils for use in sufiicientconcentration for practical applications. The amine of choice is abranched chain C to C primary amine in which the hydrocarbon chain isderived from propylene tetramer or a light isobutylene polymer. Suchamines are available commercially, for example, Primene J. M. R. amineof Rohm & Haas.

Other high aliphatic primary amines, however, may be used as long as theresultant product is soluble in oil. Thus, primary amines containinglong, usually branched, chains of C to C in length have value.

Benzoic acid is particularly valuable as the aromatic acid component inthe invention, but other aromatic acids possess useful rust inhibitingproperties, e. g. salicyclic, phthalic, toluic and cinnamic acids. Theamine-aromatic acid combination may be preformed as the amine salt ofthe acid and dissolved in the hydrocarbon oil base for the rustpreventative composition, or the amine and aromatic acid components canbe added separately to the base oil so that the product is formed insitu. In either case, we have found that the desired proportion of theamine-aromatic acid product is suitably in the range of about 8 to about12% by weight.

The zinc naphthenates employed are Zinc soaps of naphthenic acid, i. e.,the C to C cyclic acids averaging about 150 to 250 in molecular weightwhich are recovered from naphthenic type crudes by caustic washing. Theproducts commercially available are variable in zinc content and usuallycontain about 8 to 14% zinc. About 14 to about 28% by weight of zincnaphthenate, based on a concentration of zinc of about 8% by weight, maybe used in formulating the compositions of the invention.

The base oil may comprise a light lubricating oil distillate, e. g. aneutral oil, with advantage. Heavier lubricating oil fractions, however,may be used and kerosene or various light hydrocarbon solvents may beused to cut the finished compositions back to the desired viscosity forconvenient application by dipping, spraying Patented F eb. 24, 1959 orbrushing. A particularly well balanced formulation may contain about 8to 12% of the amine-'benzoate product, about 20 to 28% of zincnaphthenate (8% Zn), about 50 to of a lubricating oil of 60 to .100 SSUat F., and about 12 to 20% of a solvent naphtha such as Stoddardssolvent.

In evaluating the compositions of the invention, rep resentative sampleswere formulated and tested by means of a specially devised corrosiontest .for rating performance of rust inhibitors in strongly acidatmospheres. The procedure was conducted as follows: Three steel :ballbearings were placed in .a gooch crucible 1" high by 1% diameter at thebottom. The crucible and ball bearings were slushed for one minute inhot naphtha to remove foreign material. The crucible and ball bearingswere set on an absorbent paper for about /2 hour to allow cooling toroom temperature and evaporation of the solvent. These were then slushedfor one minute in the rust preventive compound and allowed to drain .fortwo hours on a fresh piece of absorbent paper. The speciments were thenplaced in a dessicator which was prepared in the following manner Onehundred ml. of 5% acetic acid solution was placed in a 100 ml. beakerwhich in turn was placed in a crystallization dish 2" high by 4"diameter The dish was filled with water and the assembly placed in thebottom of the dessicator. The porcelain table was supported on its edgeswith corks in the dessicator to raise it above the beaker containing theacid. The crucible and balls were set on this porcelain table and thecover to the dessicator put in place. The test was run at roomtemperature, and the ball bearings were checked daily for presence ofrust.

In the following examples, the amine used was Primene J. M. R. which isa mixture of tertiary alkyl primary amines predominating in C H NH butranging up to C H NH Physical tests on the amine included: 5-70% over at262 to 315 C., specific gravity at 25 C. of 0.845, refractive index at25 C. of 1.460 and flash point of 260 F.

In one method of preparation, the amine: and benzoic acid wereseparately incorporated in the base oil, and the mixture was stirred atF. until no crystals remained in solution. In a second method ofpreparation, the amine-benzoate product was formed by combining one moleof the amine with two moles of acid. The materials were stirred andheated at 150 F. for a few minutes at which point the addition ofbenzoic acid to the amine was complete. The resultant product was ahoney-like material in consistency and odor. In preparing the additiveproduct, temperatures of about 200 F. or more are to be avoided since atthat temperature, water is eliminated and the amide is formed.

The data of Table I below indicate by comparison the superiority ofcompositions of the invention containing the amine-benzoate additivewhen used in conjunction with greater than about 12-16% by weight ofzinc naphthenate. It will be noted that zinc naphthenate alone isineffective in inhibiting rusting of steel in acid atmospheres. Althoughthe formulation made without use of an amine showed activity, the samplehad to be applied carefully as a suspension. The additives in the testdid not remain in solution, and such formulations lack prac' ticalutility. Use of the amine-benzoic acid combina tion, however, Whetherpreformed or produced in situ in the base oil, eliminates the problem ofsolubility en countered with the use of the acid alone while providing asignificantly superior rust preventative composition. When lowpercentages of the amine-acid combination are used, the inhibitingeffectiveness of the composition is markedly reduced. See, for example,sample 6. At least about 8% of the additive product should be used forsatisfactory results.

Table 1 Zn Naphthenate (14.5% Zn) 26.3 o 0 o 24 0 0 o 0 Zn Naphthenate(Nuodex 8% Zn) 0 4 12 16 24 0 24 24 24 24 Pale on. so ssU at 100 o 70 e254 50 50 55 55. a 50 50 White 011 50 0 o 0 0 o 0 0 e r 0 0 SolventNaphtha. 15. 15 1c 16 16 15 1c 16 16 16 Sodium Sulionato 2. 5 0 0 0 0 o0 0 0 o Prlmenc J. M. R. o 5.25 5.25 5. 25 5.25 5. 25 2.62 0 0 0 BenzoicAcid 4.7 4.75 4. 75 4.75 4. 75 4.75 2.38 4.7 0 0 Primene-Benzoic AcidProduct 0 0 0 0 0 0 0 0 0 Appearance Prectipticlear clear clear clearclear clear Preciigti a clear clear a e 1 Days to rust in AcidAtmospheres. 14 7 14 i 21 18 3 14 3 1 All proportions are percent byweight of the total composition. 7 We claim: faces in acid atmospheresconsisting essentially of a lubri- 1. A rust preventative composition ofthe slashing oil eating oil distillate as base and containing dissolvedtype characterized by capacity for protecting metal surtherein about 8to about 12% in combination of a C faces in acid atmospheres consistingessentially of a hyto C aliphatic branched chain primary amine andbendrocarbon oil as base and containing dissolved therein zoic acid,about 14 to about 28% of zinc naphthenate about 8 to about 12% incombination of a higher aliand about 12 to about 20% of a solventnaphtha. phatic primary amine containing about 18 to 24 carbonReferences Cited in the file of mi a n atoms and an aromatic acid, andabout 14 to about 28% s p m t f Zinc naphthenate. UNITED STATES PATENTS2. The composition of claim 1 in which the amine is 2,333,206 Sloan Nov.2, 1943 a C to C aliphatic branched chain primary amine. 2,401,993Wasson et al June 11, 1946 3. The composition of claim 1 in which theacid is 2,415,353 Johnston et al. Feb. 4, 1947 benzolc acid. 2,587,777Smith Mar. 4, 1952 4. A rust preventative composition of the slushingoil 2,615,815 Galvin et a1. Oct. 28, 1952 type characterized by capacityfor protecting metal sur- 0 2,629,649

Wachter et al. Feb. 24, 1953

1. A RUST PREVENTATIVE COMPOSITION OF THE SLUSHING OIL TYPECHARACTERIZED BY CAPACITY FOR PROJECTING METAL SURFACES IN ACIDATMOSPHERES CONSISTING ESSENTIALLY OF A HYDROCARBON OIL AS BASE ANDCONTAINING DISSOLVED THEREIN ABOUT 8 TO ABOUT 12% IN COMBINATION OF AHIGHER ALIPHATIC PRIMARY AMINE CONTAINING ABOUT 18 TO 24 CARBON ATOMSAND AN AROMATIC ACID, AND ABOUT 14 TO ABOUT 28% OF ZINC NAPHTHENATE.